[The pathways of the stabilization of the amplitude of postsynaptic potentials in the interneuronal synapses of vertebrates]. / Puti stabilizatsii amplitudy postsinapticheskikh potentsialov v mezhneironnykh sinapsakh pozvonochnikh.

The influence of various factors on the degree of stabilization of postsynaptic potential amplitude has been studied by mathematical modelling. Increasing of transmitter release probability in single boutons, spatial non-uniformity of these probabilities, interaction of release sites, non-linear summation of potentials lead to amplitude stabilization. Temporal fluctuations of the release probability, failures of responses from contact groups and activation of a variable number of the fibers have the opposite influence. Comparison of synaptic transmission parameters in sensorimotor synapses of Cyclostomata, amphibians and mammals showed that during evolution of these synapses two different pathways of amplitude stabilization had been realized. Formation of highly effective chemical contacts is probably the most progressive pathway among them.

[An analysis of the functional heterogeneity of the sensory motor neuron synapse of the frog]. / Analiz funktsional'noi neodonorodnosti sensomotoneironnogo sinapsa liagushki.

Four models of the amplitude fluctuations of postsynaptic potentials have been compared. Better agreement of convolution of the two binomial distributions and beta-model as compared to the binomial model is demonstrated. The beta-model is based on the assumption that the probability of the transmitter quantum release is a random variable which has beta distribution. The number of the quantum generators estimated by the beta-model is close to the number of synaptic boutons in the sensory-motor synapses of the frog. Investigation of this model has shown that the number of generators estimated by the binomial model may be interpreted as the number of transmitter release sites functioning with probabilities exceeding 0.2. Results obtained confirm the hypothesis concerning the functional heterogeneity of release sites at the frog interneuronal synapses.

[Brain cholesterol in representatives of different vertebrate classes]. / Kholesterin golovnogo mozga u predstavitelei razlichnykh klassov pozvonochnykh.

Studies have been made on the cholesterol content of the brain in 73 species of vertebrates. Cholesterol content increases in both aquatic and terrestrial animals in evolutionary row. Significant variations in cholesterol content were noted within the same class. Comparative studies revealed correlation between changes in phospholipids and cholesterol on one hand and various glycolipids on the other. It is suggested that cholesterol content of the brain in vertebrates depends on ecological factors rather than on taxonomic position of animals.

[Quantal analysis of the postsynaptic potentials in interneuronal synapses: the recovery of the signal from the noise]. / Kvantovyi analiz postsinapticheskikh potentsialov v mezhneironnykh sinapsakh: vydelenie signala iz shuma.

Discrete distributions of the elementary EPSP amplitude in the interneuronal synapses of vertebrates were obtained by the maximum likelihood method. The equality of the intervals between values of the computed densities testifies to the quantal nature of the signal. The binomial model approximating the empirical distributions is revealed to be able to distinguish quantal levels of the nerve impulse transmission. These levels are conditioned by the structural organization of the interneuronal connections. Systematical differences between empirical distributions and the model necessitate generalization of the latter.

[An analysis of transmission in the interneuronal synapses using a convolution of binomial distributions]. / Analiz peredachi v mezhneironnykh sinapsakh s pomoshch'iu svertki binomial'nykh raspredelenii.

The convolution of two binomial distributions has been used for the analysis of the discrete distributions of the elementary EPSPs amplitude in the sensorimotor, proprio- and reticulo-motoneuronal synapses of the frog. It is shown that the quantity of the working transmitter release sites is higher than that estimated by the binomial distribution. The probability of the release sites response to the single action potential was unequal. In most sites they did not exceed 0.1-0.3 and were supported on the constant level. The effect on the transmitter release mechanism induced blocking of the release sites. The disturbance of preparation to the transmitter release sharply decreased the probability of the release sites response.